donation. 1  an act or instance of presenting something as a gift, grant, or contribution. 2  a gift, as to a fund; contribution.
A black or brown tongue typically is due to the overgrowth of bacteria that normally are present on the tongue. This, too, can be caused by the killing of some bacteria with antibiotics so other bacteria overgrow. But the most common cause of discoloration of the tongue is the overgrowth of a fungus. The most common fungus is called candida. But overgrowth of the candida fungus turns the tongue white. Infection with candida is called candidiasis, and when it happens on the tongue the condition is called thrush.
The tongue gets coated with tiny white or yellow coating due to bacterial infection. For severe case of infection it can cause tongue pain and bad breathe. You will get burning sensation and pain if white covering is due to yeast infection like oral thrush.